Looptaker drive for a sewing machine

ABSTRACT

A sewing machine is disclosed including a magnetic drive for a looptaker. Rare earth or similar magnets mounted on the looptaker may be driven by spaced magnets of opposite polarity without the necessity for positive mechanical connection between the sewing machine drive and the looptaker. Since a positive mechanical drive for the looptaker is obviated by this invention, the space requirement in a cylinder bed or swing bed sewing machine are advantageously optimized. This invention has particular utility when used with a looptaker capable of concatenating thread in the formation of stitches when driven in an untimed relation relatively to the reciprocation of the sewing needle with which it cooperates.

United States Patent [191 Johnson 1 Oct. 14, 1975 [75] Inventor: Ralph E. Johnson, Convent Station,

[73] Assignee: The Singer Company, New York,

22 Filed: July 24, 1974 21 Appl. No.: 491,598

[52] US. Cl. 112/184; 112/260; 310/103 [51] Int. Cl. D05B 57/14 [58] Field of Search 112/181, 182, 184, 117,

ll2/l2l.l5, 228, 231, 260, 2, 63; 57/100 [56] References Cited UNITED STATES PATENTS 1,150,123 8/1915 Jerram 112/36 2,243,211 5/1941 Kiemer 112/2 3,183,385 5/1965 Gabriel 310/103 3,573,517 4/1971 Osterstrom 310/103 Primary ExaminerWerner H. Schroeder Assistant Examiner-Conrad L. Berman Attorney, Agent, or FirmMarshall J. Breen; Edward L. Bell; Robert E. Smith [57] ABSTRACT A sewing machine is disclosed including a magnetic drive for a looptaker. Rare earth or similar magnets mounted on the looptaker may be driven by spaced magnets of opposite polarity without the necessity for positive mechanical connection between the sewing machine drive and the looptaker. Since a positive mechanical drive for the looptaker is obviated by this invention, the space requirement in a cylinder bed or swing bed sewing machine are advantageously optimized. This invention has particular utility when used with a looptaker capable of concatenating thread in the formation of stitches when driven in an untimed relation relatively to the reciprocation of the sewing needle with which it cooperates.

5 Claims, 5 Drawing Figures US. Patent Oct. 14,1975 Sheet1of2 3,911,841

U.S. Patent Oct. 14,1975 Sheet2of2 3,911,841

LOOPTAKER DRIVE FOR A SEWING MACHINE BACKGROUND OF THE INVENTION The invention disclosed by this application finds utility in cylinder bed sewing machines, in swing bed sewing machines as shown in the drawings, and, in other sewing machines where the amount of space which may be taken up by the lower sewing instrumentalities is limited. In the US. Pat. No. 1,150,123 of Jerram, issued on Aug. 17, 1915, is disclosed a lockstitch swing bed sewing machine, which has heretofore required direct connection between the sewing machine drive and the looptaker in order to maintain a timed relationship for successful stitch formation. The result as can be seen in the above noted patent is an expensive, complex and bulky arrangement.

In this invention a drive for the sewing machine looptaker includes a magnetically interacting coupling which spans an air gap through which the work fabrics being stitched may extend. As a result, the drive for the looptaker is not required to extend completely within the support, but may be directed through a subbase or the like thus providing greater freedom in the design'of the work support.

SUMMARY OF THE INVENTION In the US. Pat. No. 3,386,401 issued June 4, 1968, to R. E. Johnson, a looptaker is disclosed capable of operation in an untimed relationship with the sewing needle successfully to form stitches. One aspect of the present invention provides a unique combination of a looptaker of the type disclosed in the above patent of Johnson, with a drive for the looptaker including magnetically interacting coupling elements between which an air gap is defined. With this unique combination the positive mechanical connection of the looptaker to the sewing machine may be eliminated and inasmuch as a specific time relationship between the sewing needle and the looptaker is no longer required, the looptaker may be driven by the magnetic coupling through rotating driver magnets spaced across a wide air gap from driven magnets mounted on the rotatable looptaker. By

use of this invention, work fabrics may be interposed in the air gap and the space requirements of a positive mechanical looptaker drive are obviated.

DESCRIPTION OF THE DRAWINGS Having thus set forth the nature of the invention, reference is made to the drawings in which:

FIG. 1 depicts a swing bed sewing machine equipped with the invention in which the free ended work supporting limb is placed in a feed-up-the-arm position,

FIG. 2 depicts a portion of the sewing machine shown in FIG. 1, with, however, the free ended work supporting limb placed in a position to operate as a cylinder bed machine,

FIG. 3 depicts a portion of the sewing machine shown in FIG. 1 but with free ended work supporting limb placed in a feed-off-the-arm position,

FIG. 4 is a cross section in plan of the sewing machine as shown in FIG. 2, and

FIG. 5 is a cross section taken substantially along the line 55 of FIG. 4.

In FIG. 1 is shown a sewing machine having a bracket arm portion 11 and a subbase portion 12. The bracket arm 11 supports a top cover 14, a tension mechanism 15, a take up 16, a feeding presser foot mechanism 17, a needle bar 18 having a sewing needle 19 affixed to the end thereof, as well as other instrumentalities required for their operation as is well known in the sewing machine art.

The subbase 12 supports at its extremity a C-shaped work supporting bed 20 having a free end work supporting upper limb 21, and a lower limb 22 pivoted to the subbase 12 in a particular way, to be described below, in order to maintain the sewing needle 19 in cooperative arrangement with other sewing instrumentalities supported in the upper limb 21. A column 23 connects the upper limb 21 and the lower limb 22 opposite the free end of the upper limb leaving a work accommodating space below the free end of the upper limb.

In FIGS. 4 and 5 the details of construction of the work supporting bed 20 are depicted. Referring to FIGS. 4 and 5 it will be noted that the work supporting bed is supported on a large diameter bearing 25 on the subbase 12 through a large diameter rabbet 26 in the lower limb 22 of the work supporting bed 20. The outer periphery 28 of the bearing 25 in the subbase 12 has five equally spaced pins 29 pressed into holes 30 drilled into the subbase. A first toothed belt 31 passes about the outer periphery 28 of the large diameter bearing 25 with the pins 29 acting as cogs meshing with the teeth of the belt 31. The belt 31 also passes about a first pulley 33 affixed to one end of a shaft 34. The shaft 34 is supported by a pair of bosses 36 extending laterally in the column 23. A second pulley 38 is affixed to the opposite end of shaft 34 with the bosses 36 trapped between the first pulley 33 and the second pulley 38 to thereby limit end play of the shaft 34. A second toothed belt 40 extends from the second pulley 38 through the free ended work supporting upper limb 21 to pass about a rabbet 44 in a disc 41, the rabbet 44 also having five equally spaced pins 42 supported in holes 43 about the periphery of the rabbet. The pins 42 act as cogs meshing with the teeth of the second toothed belt 40. The disc 41 is supported in a discontinuous circular groove 45 cut into the end of the upper limb 21 and support post 46. The discontinuity of the circular groove 45 allows passage for the second toothed belt 40 as well as other instrumentalities. A work support plate 48 having an opening 49 for penetration by the sewing needle 19 in the formation of zigzag stitches, and a rotation restraining plate 50 whose purpose will be described below, are fastened to the disc 41 by screws 51.

By design the ratio of the diameter of the outer periphery 28 of the bearing 25 in the subbase 12 and the first pulley 33 is identical to the ratio of the diameters of the rabbet 44 in the disc 41 and the second pulley 38. Thus as the work supporting bed 20 is rotated from the position shown in FIG. 2 to the positions shown in FIGS. 1 or 3, the position of the disc 41, rotation restraining plate 50 and throat plate 48 remains fixed with respect to the subbase 12; and, therefore, the

bracket arm portion 11 thereby maintains alignment of the sewing needle 19 with the opening 49 in the work supporting plate 48.

A looptaker having magnets 56 attached thereto is freely rotatable on shouldered screw 57 threaded into a lug 58 in the base of the work supporting upper limb 21. The lug 58 is concentric with the circular groove 45 and disc 41. A bobbin case 60 is carried by the looptaker 55 and is kept from rotation by the rotation restraining plate 50 noted above.

The rotation restraining plate 50, the looptaker 55 and the bobbin case 60 are fashioned as disclosed in the US. Pat. No. 3,386,401, issued on June 4, 1968 to Johnson which is hereby incorporated by reference and made a part of this application. Thus the looptaker 55 is fashioned with a multiplicity of beaks 62 according to the principles set forth on page 1 1, line 22-62 of the above patent, and the bobbin case 60 is constructed as described in the above patent in order to store the needle thread loop seized by a particular hook beak in a position on the bobbin case in which it will be unaffected by the remaining hook beaks.

The use of a looptaker and bobbin case which may be operated not in predictably timed relationship with the sewing needle is required where there exists a potential for some variation in the positional relationship between the looptaker and the sewing needle. In the swing bed sewing machine illustrated in the drawing, there is obvious advantage in space saving and simplification to forgo the usual direct connection between the looptaker and the sewing machine drive. Instead, a driver 65 located in the lower limb 22, is concentric with and spaced from the looptaker 55 and supports driver magnets 66 attached to the driver in cooperative relationship with the magnets 56 attached to the looptaker. Specifically, the magnets 56 attached to the looptaker 55 may have all their south poles attached to the looptaker, while the magnets 66 attached to the driver 65 may have all their north poles attached to the driver, so that the south poles of the driver magnet 66 will be magnetically coupled with the north poles of the looptaker magnets 56.

The driver 65 is driven from a vertical arrn shaft 70 connected to the sewing machine drive to provide a maximum speed ratio of sewing needle to looptaker and/or driver as noted above according to the principles set forth in the US. Pat. No. 3,3 86,401 of Johnson. A belt 71 extends from a pulley 72 mounted on the vertical arm shaft 70 to a pulley 73 concentric to the driver 65 but located in the sub-base 12. A stud shaft 75 emanates from the pulley 73 and is connected to the driver 65 by an integral washer and screw thread 76. A bearing block 78 pressed into the lower limb 22 supports the upper end of the stud shaft 75 and driver 65 attached thereto. The pulley 73 contains a bearing cavity 79 supported on a bearing stud 80 affixed to the subbase 12 by screws 81 through four ears 82, two of which are shown in section. An adjusting screw 83 is provided to remove end play in the assembly by elevating the driver 65 against the bearing block 78.

Thus as a sewing machine drive is operated, the vertical arm shaft 70 is caused to rotate, which through the pulley 72, belt 71, pulley 73 and stud shaft 75 causes the driver 65 to rotate. By virtue of the magnetic coupling of the driver magnets 66 with the looptaker magnets 56, the looptaker 55 is caused to rotate. Although in the accompanying drawings of a preferred embodiment, a loop taker is described which is capable of operating in untimed relation with the needle reciprocation, it is also possible to utilize a drive in accordance with this invention with a looptaker which is required to be operated in timed relation. With such a timed looptaker, an arrangement of magnets should be selected which provides an operative stitch forming relationship between the loop taker and the needle in any possible locked relation between the driver and driven magnets. If, for instance, a conventional timed loop taker is used with a single beak, a single pair of magnets may be necessary to provide the required phase relationship. Depending upon the timed relation of loop taker motion with respect to needle reciprocation, and the number of loop taker beaks which are employed, an appropriate number of magnet pairs may be employed. It will be appreciated, moreover, that where a loop taker requiring timed relationship with needle reciprocation is employed, the air gap should be reduced to the barest possible minimum in order to deter the possibility of disruption in the drive.

Having thus set forth the nature of this invention, what is claimed herein is:

1. In a sewing machine having a bed, a bracket arm supported in overhanging relationship to said bed, an endwise reciprocatory needle carried in said bracket arm, actuating mechanisms imparting endwise reciprocation to said needle, a looptaker journaled in said bed in cooperative relationship with said needle, said looptaker having at least one loop taking beak, drive means carried in said bed and operatively connected to said actuating mechanism, at least one pair of magnetically interacting coupling elements for each loop taking beak, said magnetically interacting coupling elements including a driving element operatively connected to said drive means and a driven element united with said looptaker, said magnetically interacting coupling elements providing an operative stitch forming relationship between said looptaker and said needle in any possible locked relation between said driving and said driven elements, said magnetically interacting ele-. ments being arranged in spaced relation having therebetween an air gap capable of accommodating work; fabric being stitched.

2. In a sewing machine having a bed, a bracket arm supported in overhanging relationship to said bed, an endwise reciprocatory needle carried in said bracket arm, actuating mechanism imparting endwise reciprocation to said needle, a looptaker journaled in said bed in cooperative relationship with said needle, said looptaker being of a variety cooperable in untimed relationship with said reciprocatory needle in the formation of stitches, drive means carried in said bed and operatively connected to said actuating mechanism, magnetically interacting coupling elements including a driving element operatively connected said drive means and a driven element united with said looptaker, said magnetically interacting elements being arranged in spaced relation having therebetween an air gap.

3. In a sewing machine having a frame base, a bracket arm secured to said frame base, an endwise reciprocatory needle carried in said bracket arm, an actuating mechanism imparting endwise reciprocation to said needle, a cantilever work supporting bed overhanging said frame base and defining a work accommodating space therebetween, a looptaker joumalled in said cantilever work supporting bed for cooperation with said needle in the formation of stitches, said looptaker cooperable in untimed relationship with said reciprocatory needle in the formation of stitches, drive means for said looptaker crried in said frame base and operatively connected to said actuating mechanism, magnetically interacting coupling elements including a driving element operatively connected said drive means and a driven element united with said looptaker, said magnetically interacting elements being arranged in spaced relation to define therebetween an air gap traversing said work accommodating space.

4. In a sewing machine having a frame base, a cantilever work supporting bed arranged to overhang said frame base and define a work accommodating space therebetween, means pivotably supporting said cantilever work supporting bed relatively to said frame base to swing about an axis which traverses said work accommodating space, a bracket arm secured to said frame base, an endwise reciprocatory needle carried in said bracket arm, an actuating mechanism imparting endwise reciprocation to said needle, a looptaker journaled in said cantilever work supporting bed for cooperation with said needle in the formation of stitches, said looptaker cooperable in untimed relationship with said reciprocatory needle in the formation of stitches, drive means for said looptaker carried in said frame base and operatively connected to said actuating mechanism, magnetically interacting coupling elements including a driving element operatively connected said drive means and a driven element united with said looptaker said magnetically interacting elements being arranged in spaced relation to define therebetween an air gap traversing said work accommodating space.

5. In a sewing machine having a frame including a subbase, a bracket arm secured to said subbase, an endwise reciprocatory needle carried in said bracket arm, a C-shaped work supporting bed member including spaced substantially parallel limbs, means joumaling the free extremity of a first of said spaced limbs of said bed member on said frame subbase, a looptaker carried in the free extremity of a second limb of said bed member, and means for imparting stitch forming movement to said looptaker including magnetically interacting coupling elements carried one in said second bed member limb and drivingly connected with said looptaker, and the other in said subbase and drivingly interconnected with said reciprocating needle, and with an air gap separating said coupling elements and spanning said free space between the limbs of said bed member. 

1. In a sewing machine having a bed, a bracket arm supported in overhanging relationship to said bed, an endwise reciprocatory needle carried in said bracket arm, actuating mechanisms imparting endwise reciprocation to said needle, a looptaker journaled in said bed in cooperative relationship with said needle, said looptaker having at least one loop taking beak, drive means carried in said bed and operatively connected to said actuating mechanism, at least one pair of magnetically interacting coupling elements for each loop taking beak, said magnetically interacting coupling elements including a driving element operatively connected to said drive means and a driven element united with said looptaker, said magnetically interacting coupling elements providing an operative stitch forming relationship between said looptaker and said needle in any possible locked relation between said driving and said driven magnet, said magnetically interacting elements being arranged in spaced relation having therebetween an air gap capable of accommodating work fabric being stitched.
 2. In a sewing machine having a bed, a bracket arm supported in overhanging relationship to said bed, an endwise reciprocatory needle carried in said bracket arm, actuating mechanism imparting endwise reciprocation to said needle, a looptaker journaled in said bed in cooperative relationship with said needle, said looptaker being of a variety cooperable in untimed relationship with said reciprocatory needle in the formation of stitches, drive means carried in said bed and operatively connected to said actuating mechanism, magnetically interacting coupling elements including a driving element operatively connected said drive means and a driven element united with said looptaker, said magnetically interacting elements being arranged in spaced relation having therebetween an air gap.
 3. In a sewing machine having a frame base, a bracket arm secured to said frame base, an endwise reciprocatory needle carried in said bracket arm, an actuating mechanism imparting endwise reciprocation to said needle, a cantilever work supporting bed overhanging said frame base and defining a work accommodating space therebetween, a looptaker journalled in said cantilever work supporting bed for cooperation with said needle in the formation of stitches, said looptaker cooperable in untimed relationship with said reciprocatory needle in the formation of stitches, drive means for said looptaker crried in said frame base and operatively connected to said actuating mechanism, magnetically interacting coupling elements including a driving element operatively connected said drive means and a driven element united with said looptaker, said magnetically interacting elements being arranged in spaced relation to define therebetween an air gap traversing said work accommodating space.
 4. In a sewing machine having a frame base, a cantilever work supporting bed arranged to overhang said frame base and define a work accommodating space therebetween, means pivotably supporting said cantilever work supporting bed relatively to said frame base to swing about an axis which traverses said work accommodating space, a bracket arm secured to said frame base, an endwise reciprocatory needle carried in said bracket arm, an actuating mechanism imparting endwise reciprocation to said needle, a looptaker journaled in said cantilever work supporting bed for cooperation with said needle in the formation of stitches, said looptaker cooperable in untimed relationship with said reciprocatory needle in the formation of stitches, drive means for said looptaker carried in said frame base and operatively connected to said actuating mechanism, magnetically interacting coupling elements including a driving element opeRatively connected said drive means and a driven element united with said looptaker said magnetically interacting elements being arranged in spaced relation to define therebetween an air gap traversing said work accommodating space.
 5. In a sewing machine having a frame including a subbase, a bracket arm secured to said subbase, an endwise reciprocatory needle carried in said bracket arm, a C-shaped work supporting bed member including spaced substantially parallel limbs, means journaling the free extremity of a first of said spaced limbs of said bed member on said frame subbase, a looptaker carried in the free extremity of a second limb of said bed member, and means for imparting stitch forming movement to said looptaker including magnetically interacting coupling elements carried one in said second bed member limb and drivingly connected with said looptaker, and the other in said subbase and drivingly interconnected with said reciprocating needle, and with an air gap separating said coupling elements and spanning said free space between the limbs of said bed member. 